Pump and motor hydraulic system, including reversing and automatic by-pass valve units



Sept. 15, 1953 M. cHATTLl-:R 2,651,915

PUMP AND MOTOR HYDRAULIC SYSTEM, INCLUDING REVERSING AND AUTOMATICBY-PAss VALVE UNITS Filed Aug. 22, 1949 Patented Sept. 15, 1951 PUMP ANDMOTOR HYDRAULIC SYSTEM, INCLUDING REVERSING AND AUTOMATIC BY-PASS VALVEUNITS Leo M. Chattler, Washington, D. C.

Application August 22, 1949, Serial No. 111,753

2 Claims. (Cl. 60-52) (Granted under Title 35, U. S. Code (1952),

sec. 266) This invention relates to hydraulic systems in general and inparticular to hydraulic systems which may be used on aircraft and whichinclude a plurality of open center six port control valves arranged inseries for center iioiv of the fluid through the system and in parallelfor unit operation.

The general object of the invention is to provide a variable volume pumpoperated hydraulic system which will automatically unload the entirehydraulic system pressure when none or" the hydraulic services arerequired.

It is also an object of the invention to provide such a hydraulic systemin which, `when any hydraulic service is required, the initial operationof any control valve automatically pressurizes the hydraulic system andmaintains it under pressure until the unit operation is completed.

It is a further object of the invention to provide such a hydraulicsystem in which, when any unit operation is completed the systemautomatically returns to the circulatory back pressure oi the opencenter circuit.

Other objectives will be obvious or apparent from the followingdescription and in the drawing hereto appended in which Fig. 1 showsschematically the arrangement of a plurality of open center, six port,control valves and a pressure operated dump Valve in hydraulic circuitrelationship to a variable volume pump and reservoir; and Fig. 2 shows adetail of the valve system.

The present day or prior art method of performing the operation of anopen center type system consists essentially in flowing hydraulic fluidthrough a series circuit of open center control valves with return tothe reservoir. The operation of any control valve automatically directsthe uid into the operating circuit and the unit operation is performed.Manual return of the control valve to neutral position is required inorder to drop the system pressure.

The disadvantages of the prior art method are:

l. It is a priority system in that the operation of only one circuit ata time may be allowed.

2. Larger lines are required in order to obtain draulic system forcontrol and operation of vari-4 ous functional units of an aircraft areshown and wherein, a reservoir for hydraulic fluid is indicated at lil.This reservoir is connected to the suction side of variable volumedelivery pump |2 by conduit I4. The fluid delivery of pump l2 is'- ledby conduit IS to inlet port I8 of pressurel responsive dump valve 20.This valve may be any conventional type of dump valve which hasy thecharacteristic of bleeding oi from 5% to 10% of the delivery received toone conduit circuit, returning the balance to the system reservoirthrough conduit 32 when this conduit circuit is open and of feeding theentire received delivery into a high pressure conduit system when thesaid return of the balance to the reservoir is blocked by back pressuredeveloped by the cutting off of flow through the open circuit conduitsystem.

Valve 29 bleeds oi from about 5% to about 10% of the hydraulic fluiddelivered to it from pump l2 feeding this minor proportion va conduit 22to open center inlet port 24 of six port control Valve 26 which when innon-operating position feeds the hydraulic fluid through its center andout through outlet port 28 to other similar control valves in series toconduit 30 by which the fluid is returned to the system reservoir I0.When this center flow circuit is in operation pressure on the hydraulicuuid in the hydraulic system drops to a relatively low magnitude.

Reference is here made to Fig. 2 and to copending application of thisinventor Serial No. 111,754, iiled August 22, 1949, now Patent2,530,377, as drawn to the siX port center flow control valve unit 26used in the hydraulic system of the instant application. This controlvalve unit comprises a valve casing 2B, inlet and outlet ports 36 and5l, respectively, in the casing, a chamber 5l) within the casing, areciprocable valve 6| within said chamber having bearings in the endwalls of the valve body, two chambers 62 and 63 within said reciprocablevalve separated by a partition wall, a spool 64 projecting into said twochambers and mounted for reciprocation in said partition wall, aperforate piston 65 in each chamber mounted on said spool and dividingeach chamber into two compartments, annular grooves 66, 61, 68, 69, l0and 'ii in the periphery of said reciprocable valve spaced with respectto the inlet and outlet ports 36 and 5l, channels 72, 13, lll, l5, 'i6and Ti in said reciprocable valve connecting said annular grooves withthe said compartments, a transverse channel in said valve positionedmidway between the ends thereof, an annular groove 8| positioned on saidspool midway between the pistons thereon and resilient means 82 mountedon said spool for automatically moving said spool for registration ofsaid annular groove 8i with said transverse channel 80 when the pressureon both sides of said motor piston is equalized. It is noted that inletport 24 has upper and lower conduits 2 and 3 corresponding to upper andlower conduits 4 and 5 of outlet port 28, the conduits 2 and Elconnecting with channel S at the .up position of Valve 6| and conduits 3and 5 connecting with channel 80 at the down position of this valve.

The valve 2S also includes outlet port 33 connected to valve compartment63 by duct 1T and leading by conduit 4S to one end of servo-motor 42wherein piston 45t and piston rod 46 will be moved to the left tooperate the desired mechanism, as shown in Fig. 1. The other end oi theservo-motor has a conduit connection 48 to the port 50 at the left upperside of valve unit 26, this port having connection with the groove 6,3,when the valve Si is at its upper limit. Conduit l2 connects groove G5to compartment 52. Referring to valve in greater detail, a housing |00is provided having inlet port ES connected to the pump conduit i andoutlet port 33 connected to the main conduit 34 feeding to the controlvalve system. The housing also has a return port 54 associated with theoutlet port 5G connecting the reservoir conduit 32. A central bore inthe housing |00 contains a sleeve and spoel assembly, the sleeve |02being fixed in the bore and the spool |03 being slidable in bore lei ofthe sleeve. The. spool has an enlarged head at the lower end andhollowed to form an inverse cup itt adapted to receive a coil spring |05which normally tends to move the spool into the sleeve.

The spool has also a central bore itil' extending from the enlargedopening |03 in the terminal cup |04 to a small cavity |09 at the otherend of the spool. A duct H0, in the wall of the enlarged end of thespool, connects the cupcavity |53 to the inlet port i8 so that apermanent open fluid connection between the inlet port and conduit 22 isprovided.

The bore |0i is closed at its upper end by a plug ill. This plug isfixed to the top end of thev sleeve |02 and has a central duct for fluidcommunication between the return passageway 54-55 and cavity |09 at theupper end oi the 4 spool |03. The upper end of this duct is recessed toform a seat and in this seat a valve ball |I2 is yieldingly retained bymeans of the rod follower H4 and coil spring H3 surrounding thefollower. The plug H5 fastened in the housing, in line with the sleeve|02, is hollowed to receive the casing H6 in which the rod follower issecured.

The sleeve E02 is grooved on its periphery to form a channel |20communicating directly with the outlet port 56. A channel I2I islikewise formed on the periphery of the spool |03A in such positionthat, when the spool is seated at the lower terminus of the housing, afraction of the axial channel length is open to the inlet port i8, buton upward movement of the spool in sleeve |02 this communication isclosed. A ductl |23, connects the channels |20 and |2i.

Let it be assumed that initially the valve 6| is at either limit ofmovement within valve charnber 60, as for example, at the lower end. Inthis position the channel 80 is connected with conduits 3 of inlet port263 and conduit 5 of out-let port 28 so that continuous centery i'iowthrough valve unit 2E is maintained, the servo-motor |4 being inactive,with the piston 44 at one end thereof.

When it is desired to operate any one of the functional units, forexample to lower the landing gear, the plane pilot moves the controlvalve to upper position. By this movement the Valve 6| is lifted and thecirculation of the hydraulic fluid through center channel is immediatelycut oil causing back pressure to develop in spool cavity |08 of the dumpvalve to force the spool |03 upwardly in the sleeve |02, thereby cuttingofi the main by-pass ow of iiuid in the dump valve by way of|8|2||23|2056 and thus developing pressure in dump Valve outlet 33leading to the control valve 26 and the operating circuit of the system,in the following sequence, 34-36-'15-63--11-38--load 42; load 42-48-50--72-62-13-68-5i-52. This forces perforated pistons 65 downwardlyclosing channel 30 and preventing release of pressure on the spool |03of the dump valve, when the valve reaches its upper limit in casing 21.

After work piston 44 has moved to its left limit, the pressures incylinder 42 become static and iiow ceases in compartments S2 and 63 byvirtue of spring 82 and realignment of ducts 80 and 8|. Thereupon, thepressure drops in conduit 22 and dump valve spool cavity permitting thepressure in inlet i3 to force the spool downwardly thereby openingby-pass channel i2 I--I 23-i 20- 56 and reducing the system pressure toa desirable low value. A reversal of lever 90, lowering control valvecylinder 5|, will produce a reversal in the above described action.

If excess pressure should develop in the system circuit, due, forexample, to accidental stoppage in the pipe line, the dump valve bail H2will release, permitting the spool to drop and thus opening the dumpby-pass to relieve the excess pressure. This release is momentary, theaction being repeated as long as the abnormal condition remains.

If it is desired to operate any particular unit to an intermediateposition, as in the case of feathering of a wing flap, the control valvefor that particular unit is moved to the operating position to move theflap to the desired angle. As the iiap reaches the desired angle ofinclination, the control valve is moved to a position intermediate theraise and lower" positions. In this position low oi hydraulic fluid toand from the operating unit, and center flow through the Valve isV cutoli. The entire delivery from pump I2 is returned from the inlet side ofvalve 20 acting as a relieve Valve to reservoir i0 via conflzit 32,through the release o dump valve ball The invention is therefore seen toreside in the arrangement in a hydraulic system of a plurality of opencenter six port control valves in a series circuit as to center ow ofthe hydraulic fluid and in parallel circuit as to hydraulic fluid ow inunit operation. That is to say that the hydraulic system comprises anarrangement of these control valves in both series and parallel flowcircuits whereby any one or more of the functional units may be operatedsimultaneously and when none of the functional units are in operationthe hydraulic iiuid flows through the system under a relatively lowpressure.

The invention described herein may be manufactured and used by or forthe Government of the United States of America for governmental purposeswithout the payment of any royalties thereon or therefor.

What is claimed is:

1. In a hydraulic system containing hydraulic iluid, the combination ofa reservoir for said fluid, a delivery pump in communication with saidreservoir on its suction side, a back pressure responsive dump valve forreceiving the delivery of fluid from said pump and for dividing saiddelivery into relatively large and small proportions and for conductingsaid small proportioned ow to main and by-pass outlets, said dump valvecomprising a casing having a tubular cavity, a valvular element slidablymovable in said cavity, ducts formed in the casing Wall, a conduitbetween one of said ducts and said pump, a conduit between another ofsaid ducts and said reservoir, a rst duct in said valvular elementadapted at one limit of movement of said element to pass iiuid directlyfrom the pump to the reservoir in said large proportioned iiow, a secondduct in said valvular element adapted to conduct fluid from the pumpduct to said by-pass outlet, said valvular element having an expandedpressure terminal susceptible to back pressure for moving said valvularelement to close said first duct, a valve unit including a stationarytubular section and a valve section movable inside said stationarytubular section, main and by-pass ducts in opposed sides of the casingwall, main and by-pass ducts in said movable valve section, conduitsconnecting the dump valve main and by-pass outlets to the inlets of themain and by-pass ducts of said stationary valve section, outlet conduitsfor the main and by-pass conduits of said stationary valve section,manual means for moving said movable valve section to connect saidstationary and movable main ducts and said stationary and movableby-pass ducts and to disconnect said stationary and movable by-passducts, whereby back pressure is made eective on the expanded pressureterminal of the valve element of said dump valve to cut 01T the largeproportioned now therethrough, a valve in said movable by-pass duct, afluid pressure sensitive device connected to said movable by-pass valvefor actuation thereof, a fluid pressure mechanism external to said valveunit, and a conduit connecting said uid pressure mechanism and saidpressure sensitive device, said pressure mechanism being operative toactuate said pressure sensitive device to open said movable by-pass ductwhereby large proportioned ovv through the dump valve may take place.

2. 1n a hydraulic system containing hydraulic fluid, the combination ofa reservoir for said uid, a delivery pump in communication with saidreservoir on its suction side, a back pressure responsive dump valve forreceiving the delivery of iluid from said pump and for dividing saiddelivery into relatively large and small proportions and for conductingsaid small proportioned ow to main and by-pass outlets, said dump valvecomprising a casing having a tubular cavity, a valvular element slidablymovable in said cavity, ducts formed in thecasing wall, a conduitbetween one of said ducts and said pump, a conduit between another ofsaid ducts and said reservoir, a rst duct in said valvular elementadapted at one limit of movement of said element to pass iluid directlyfrom the pump to the reservoir in said large proportioned flow, a secondduct in said valvular element adapted to conduct uid from the pump ductto said by-pass outlet, said valvular element having an expandedpressure terminal susceptible to back pressure for moving said valvularelement to close said casing reservoir duct, a valve unit including astationary tubular section having main and by-pass Wall ducts throughthe walls theerof, conduits connecting the inlet ends of said ducts tothe outlet ducts of said dump valve, and a movable valve sectionslidably movable within the tubular cavity of said stationary sectionand having a first duct and a by-pass duct communicating respectivellywith the outlets of said stationary section main and by-pass ducts,conduits connecting the outlets of the stationary section main andby-pass ducts to said reservoir, manual means for moving said movablesection to connect said stationary and movable main ducts and saidstationary and movable by-pass ducts and to disconnect said stationaryand movable by-pass ducts, uid pressure responsive valvular means insaid valve unit for closing and opening said movable by-pass ductincluding a first perforated piston slidably movable in said iirst mainduct and formed in the movable valve section, a second main duct throughsaid movable valve section, stationary wall ducts adapted to communicatewith said main duct, a second perforated piston movable in said secondmain movable duct, a slide valve rigidly connected between said rst andsecond pistons and movable therewith to open and close the by-pass ductin said movable valve section, and fluid pressure responsive meansexternal to said valve unit and connected to said valve unit duct forchanging the pressure effective on said piston slide valve, whereby thebypass duct through the movable valve unit section is opened.

LEO M. CHATTLER.

References Cited in the iile of this patent UNITED STATES PATENTS NumberName Date 2,057,087 De Millar Oct. 13, 1936 2,057,088 De Millar Oct. 13,1936 2,530,377 Chattler Nov. 21, 1950

